The invention relates to an externally suspended facade system, preferably mounted on an aluminum subsystem, according to the preamble of claim 1.
DE-PS 34 01 271 and manufacturers' brochures have disclosed a facade system whose boards are secured by means of narrow board holders to horizontal or vertical supporting sections. In this system, an H-shaped piece of the board holder engages around the head rabbet of the respectively lower board and the foot rabbet of the respectively upper board. The board holders are in general arranged in pairs at the head and foot rabbets, respectively, of the facade boards, which are preferably embodied in transverse format and are offset slightly inwards from the corners of the facade boards so that the facade boards are secured at 4 points. Since the H-shaped pieces of the board holders are active upwards and downwards, there is a requirement throughout the surface of two board holders per facade board. The disadvantage of this system lies in the high requirement of two board holders for each facade board, as a result of which both the materials costs and the labor costs for the completely installed facade system are increased. In addition, the high head rabbet in particular is exposed to a substantial risk of breaking if the facade board is subjected to a heavy impact from the front, as in this event, as a result of slight tilting of the facade board, the head rabbet rests with its top rearward edge on the board holder, so that the supporting force acts on the head rabbet with a long lever arm.
Also known from DE-PS 36 27 584 and from manufacturers' brochures is a joint section for the vertical joints of facade systems, which is intended to prevent the relative movement of the facade boards in the horizontal direction in the plane of the facade and the clattering of the facade boards in a wind. The joint section consists of a central knuckle of the width of the vertical joint provided between the facade boards and two resilient double legs arranged on both sides of the central knuckle. The joint section is mounted in long bars and so ensures clean flush fitting of the vertical joints. The disadvantage of this system lies in the fact that the joint section described, because of the necessary resilient action, must be produced from very thin material and therefore bends easily out of true during installation or requires a long assembly time if the necessary care is taken. In addition, because of the necessary 7-fold beveling, it is costly to produce. For both reasons, the production costs of the completely installed facade system are increased. A further disadvantage of this joint section lies in the fact that it provides only inadequate sealing of the vertical joint against incident rain, since the legs of the central knuckle are continued in a straight line to the support point on the supporting section and therefore narrow gaps may be left as a result of production tolerances, through which water may be driven which reaches the supporting profile and, via this, the heat insulation, and soaks the latter.